The present invention relates to telecommunication technology. In particular, the present relates to a new an improved method and system for the management of the interface between a local exchange and an access node.
Open interfaces (V5.1 and V5.2) between an access network or an access node and a local telephone exchange are defined in the ETSI (European Telecommunications and Standards Institute) standards of the ETS 300 324 and ETS 300 347 series. V5 interfaces enable subscribers belonging to a physically separate access network to be connected to a telephone exchange using a standard interface. A dynamic concentrator interface (V5.2) defined by the ETS 300 347 standard series consists of one or more (1-16) PCM (Pulse Code Modulation) lines. One PCM line comprises 32 channels, each with a transfer rate of 64 kbit/s, i.e. 2048 kbit/s altogether. The V5.2 interface supports analogue telephones as used in the public telephone network, digital, such as ISDN (Integrated Services Digital Network) basic rate and primary rate interfaces as well as other analogue or digital terminal equipment based on semi-fixed connections.
A V5 interface may comprise a maximum of 16 2-mbit/s links (PCM lines/connections). Each link in the V5 interface is marked with a link identity number, link ID. The link ID must be the same at both ends of the V5 interface, i.e. at the local exchange end and at the access node end.
A link identification procedure is used for the verification of link identifiers for a certain link. Link identification is generally started after normal operation of a link is restored after a malfunction when the V5 interface is restarted or when a request for link identification is sent via an interface for the management of the V5 interface. The V5 System Management program block of the network element is responsible for link identification. In a network element, an identification procedure for only one link may be active at a time.
Standards ETS300 377-1 (ETSI) and Q.824.5 (ITU-T draft) define a V5.2 interface link identification interface for a network element, which identification interface is started via a management interface. The response to be given to the management interface regarding link identification is accurately defined (Notification: Check Link ID Result) and the response may be: (0) link identification carried out and identification successful (Link ID OK), (1) link identification carried out and identification unsuccessful (Link ID Not OK), and (2) link identification request rejected by the network element at the other end (Link ID Rejected).
If the System Management program block is unable to start the link identification procedure in the network element whose management interface is being used to start the procedure, then a problem arises. If the computer responsible for network management which is trying to start the link identification procedure via the management interface does not receive a controlled or defined response to its request, the result is an indefinite situation where the system does not necessarily know how to proceed. This impairs the performance of the network management computers if there is no sensible response from the network element to the link identification request within a reasonable time. In addition, if the operator responsible for network management does not get an explicit response from the network element, then it will take longer and be more difficult to eliminate the malfunction.
There are many factors that may cause rejection of a link identification request locally in a network element. The link may be in a condition that prevents the activation of the link identification function; for instance, the link may have a connection failure. In addition, a link identification procedure may be going on in another link, in which case, according to the standards, other link identification requests will be rejected. The standards do not take this situation into account at all, and none of the responses described in them is applicable in the situation in question.
The object of the present invention is to eliminate the problem described above. A specific object of the present invention is to disclose a new and improved method for the management of link identification and the V5 interface so that the system will never get into an indefinite condition under any circumstances.
A further object of the invention is to disclose a method and system which provide an unambiguous and controlled function and response to link identification started via a management interface in cases where link identification is unsuccessful due to a cause detected by the V5 Interface System Management of the network element through which the link identification procedure is started.
As for the features characteristic of the present invention, reference is made to the claims.
The present invention concerns a method for the management of a V5 interface in a telecommunication system. The telecommunication system comprises a first network element, which may be a local exchange, an a second network element, which may be an access node connected via a V5 interface to the local exchange, and a management interface connected to different network elements. Moreover, the telecommunication system may comprise a cascaded V5 interface, in which case the first network element is connected to the second network element via a first V5 interface. The second network element is further connected to the local exchange via a second V5 interface.
Via the management interface, various commands in the MML command language (Man Machine Language, MML) relating to network management can be supplied to the network elements. The management interface is connected to a network for the management of the telecommunication network, the management network generally being a separate network within the telecommunication network.
In the method of the invention, link identification is carried out when a standard link identification request is supplied via a management interface to a network element, such as a local exchange or access node, or when otherwise necessary for the operation of the interface.
According to the invention, when link identification is requested locally via a management interface in one network element and when the link identification procedure cannot be started via this network element, a notification of unsuccessful link identification is given locally to the management interface.
The invention makes it possible to achieve unambiguous and controlled operation and response in a situation where link identification started via a management interface fails. There are many different causes that may lead to a failure of link identification, as described above. In addition, the invention provides a way to reduce the workload of network management computers and clarify their operation as they can be given a correct and defined response in all situations.
If a link identification process is going on for another link in the network element in question at the same time, then, in an embodiment of the invention, a new link identification request can be placed in queue in this network element and subsequently processed in due course when the condition of the network element permits it. If link identification cannot be started at all e.g. because of a failure or congestion in the link, this situation can be predicted by sending the network element an inquiry regarding the condition of the network element or link before issuing a link identification request.
If link identification fails and the network management computer or the operator receives a controlled response from a defective network element, then link identification can be started via another network element. In this case, the operator will be able to eliminate the malfunction faster, thus improving the reliability of the telephone network.
The system of the invention for the management of a V5 interface in a telecommunication system comprising a local exchange, an access node connected to the local exchange via a V5 interface, and a management interface connected to different network elements comprises means for giving a standard link identification request from the local exchange or access node.
According to the invention, the system comprises means for giving a notification of failure of link identification locally to the management interface when link identification is requested via the management interface and when link identification cannot be carried out in the network element through whose management interface the link identification request is given. The response given by the network element for controlled rejection of a link identification request could be of the form: Reject from local site. As for the advantages of the system of the present invention, reference is made to the advantages of the method presented above.
In addition, the system of the invention may comprise means for implementing queueing so that a link identification request received from the management interface can be placed in queue to wait until the network element is restored to a condition that allows link identification to be carried out. In this case, a message indicating that the link identification request has been placed in queue can be sent to the management interface. These messages can be repeated at regular intervals. The queueing provides the advantage that the network management computer need not renew its link identification request after a failure or rejection of the first request.
In an embodiment of the invention, the system may comprise means for verifying, from the network element via the management interface before giving a link identification request, the condition of the network element and link and whether it is possible to start the link identification process. This makes it possible to determine beforehand whether it is at all worth while requesting link identification in the network element in question. In this way, the occurrences of indefinite conditions in the telephone network can be reduced.
In an embodiment of the invention, the system may also comprise means for starting link identification via a second network element in the case of a failure of link identification via a first network element. This allows faster reparation of possible failure situations in the first network element.
In the following, the invention will be described by the aid of a few preferred examples of its embodiments with reference to the attached drawing, wherein